Preparation of liquid bleach solutions



Patened Aug. 22, 1922..

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PVA/W w MW www@ www I PREPARATION 0F LIQUID BLEACH SOLUTIONS.

` ation of Liquid 1o such as will enable a small scale to simply pass such solutions are unstable and JAMES n. Macramori', Arnau wenns,

0F NIAGARA FALLS, INC., 0F NEW'YYORK, N.'Y., A CQRPU'RATION 0F VIRGINIA.

NEW YOR, ASSlIQrNOR T0 THE MATHIESON PREPARATION 0F LIQUID BLEACH SOLUTIONS.`

Macnee.

.j State 0f New York, have invented certain new and useful Improvements in the Prepar- Bleach Solutions; and I do the following to be a full,

hereby declare description of the inventlon,

clear, and exact to which it appertains to make and use the same.

rl`his invention relates to improvements in the prepera-tion of liquid bleach solutions.

The manufact-ure of liquid bleach solutions by passing chlorine gas into milk-oflime, caustic soda solutions or similar alkalies has long been known. It is customary, for example, in preparing these solutions on the gas into the alkali solution in approximately chemically equivalent proportions. In making such solutions, however, the temperature should not vrise above approximately 40 C., since their rate of decomposition increases very rapidly above 40 C. For this reason it is customary to make only dilute solutions, starting Lwith a cold alkaline solution, or when more con- Specification of Letters Patent.

others skilled in the art g before it is brought into contact, directly or indirectly, with the alkaline solution.

Various methods of procedure can be followed in carrying outithe process of the invention. The liquidl chlorine can be obtained from the usual containers therefore, but these `containers should be so arranged or connected that the chlorine will be drawn 0E therefrom in a liquid state, instead of in ya aseous state, thus avoiding the vaporization of the chlorine in the containers and the lowering of temperature incident thereto. By avoiding this lowering of temperature in the chlorine container, there is likewise avoided the necessity for heating the container to neutralize the cooling effectdue to vaporization. Where the chlorine is supplied in large containers, for example, containers holding lone ton or more of liquid chlorine, the utilization of the liquid chlorine directly, according to the present invention, eliminates the necessity for the provision of an intermediate heating and vaporizing container, intermediate the large chlorine container and the alkaline solution, for heating the liquid chlorine and neutralizing its heat of vaporization. rlFhe present process, accordingly, i'n' volves a marked simplification in the manner of handling liquid chlorine heretofore emrarenr' @terreno raten-tea aug., ae, ieee. Application led March 'i1922. Serial No. 541,224.

35 ample, by adding ice, or by cooling by means i ployed, and in the expedients for handling it.

of the solution durlng the reaction is necesheretofore resorted to. sary to keep the temperature below the crit- The conducting of the liquid chlorine into,

30 centrated solutions are made, refrigeration ical point. This cooling or refrigeration of or into heat interchanging relation with. the the solution has been accomplished, for ex-l alkaline solution, can be carried out in va-v rious Ways. One advantageous method of doing this is to introduce the liquid chlorine through a Vmetal pipe coil, preferably of lead, placed in the bottom of the tank containing the alkaline solution, one end of this coil being connected to the liquid chlorine supply, and the other end being provided with a nozzle for breaking u p the stream-of chlorine gas or through an injector nozzle to circulate the liquid. lnstead of introducing the chlorine gas through a nozzle, it may be introduced through a number of small perforations arranged at intervals along the length of thepipe coil, in which case the coil may be closed at its end. `The pipe coil should be long enough to provide the necessary heat interchange, so that the liquid chlorine therein will be vaporized by the heat of the surrounding solution. The solution will itself be cooled by the low temperature at which the vaporization of the liquid of cold brine coils, or by similar methods.

According to the present invention, bleach solutions of relatively high concentration can 'be directly produced in a particularly advan- 40 tageous way without danger of objectionable overheating of the solution.

In the carrying out of the invention, liquid chlorine is employed and it is brought, while still in a liquid state, directly into, o r into 45 heat interchanging relation with, thel alkaline solution with which it is to be combined in forming the bleach solutions; and advantage is thus taken of the large amount of latent heat of vaporization of the liquid chlo- 50 rine to cool the alkalinel solution being reacted upon; thus avoiding the necessity for the employment of refrigeration by brine coils or similar expedients, and also avoiding the necessity for special provisions for 55 heating and vaporizmg the liquid chlorine chlorine takes place, so that the heat of the original solution, together with theheat ot' reactlon, will supply the heat necessary for vaporization of the liquid chlorine, and so that the vaporization of the liquid chlorine will in turn counteract the heat of reaction A and prevent the temperature from rising to vat .first vaporized and vrthen introduced in gaseous form, and particularly where the solution is rapidly agitated, e. g., by introducing the chlorine through an injector nozzle, or where the, solution is of suiiicient depth to permit substantially complete ab` Sorption of the chlorine gas introduced therein, the 'solution can be readily chlorinated and relatively strong bleach solutions produced- Without objectionable overheatlngl of the solution.

Another method of introducing the liquid chlorine into the bleach solution is to atomize the liquid chlorinein very fine streams directly into the solution. the streams being ,sufliciently finev to avoid the formation of gas bubbles of excessive size, dueto vaporization of theliquid chlorine or the alkaline solution being vigorously agitated to bring about rapid dissemination of the chlorine, when so introduced.

Another method of introducing the liquid chlorine is to atomi'ze it intovan apparatus in which the alkaline solution is sprayed or showered through a chamber or tower, so

that the liquid chlorine will be vaporized and will form a chlorine atmosphere through which the alkaline solution is showered at a temperature maintained sutliciently low by the vaporization of the liquid chlorine. The alkaline solution can be recirculated, if necessary, to further increase its strength,-or the alkaline solution can be passed down through a tower containing obstructions to retard its flow and to expose a maximum amount of surface of the alkaline solution to the gas. Instead of introducing the -liquid chlorine directly into the tower or apparatus into which the alkaline solution is introduced, the chlorine may first be passed through a pipe coil submerged in the alkaline solution to accomplishl the vaporization or partial vaporization of the liquid chlorine and the simultaneous cooling of the solution, and the solution and chlorine gas may thereafter be brought into contact with heat interchanging relation with the liquid chlorine.`

An improved apparatus embodying the invention and adapted for the practise of the process of the invention is illustrated in a somewhatv conventional and diagrammatic manner in the accompanying drawing in vertical section and withy parts in elevation.

Inthe apparatus illustrated, the mixing tank 1 has an inclined bottom and an outlet pipe 3 leading to the suction side of a pump 4, which discharges through the pipes 5 and 6, back to the mixing tank through the outlet pipe 7. A separate outlet pipe 8 is provided, also connected to the suction side of the pump, and having a pipe section 9 pivoted thereto in such a way that the upper end of the pipe 9 can be raised or lowered to permit drawing off of the clear settled chloinated liquor from different levels. The disA charge side of the pump is also connected through the pi es 5, 10 and 13 to the stock tank 14 from w ich the solution can be`withdrawn through the pipe 15 and pumped by the pump 16 thro-ugh the pipe 17, to'the place of use of the solution, A clean-out drain 18 is provided for the stock tank 14 and a similar drain pipe 19 is provided at the bottom of the mixing tank 1.

The liquid chlorine issupplied from the container 21 which may be a drum'of, for example, 1 ton capacity and is drawn oft` through the valve 22 at the bottom of the container so that vaporization of the chlorine and' drawing off of gaseous chlorine from the top of the container isavoided. The liquid chlorine passes through the pipes 23, past the expansion valve 24 and then through the chlorine pipe 20 and the coil 25. The liquid chlorine passing through the coil is heated by the surrounding liquid in the manner above described, and is itself vaporized while at the same time serving to cool the surrounding solution. The vaporized chlorine escapes from the coil 25 through the outlet nozzle 26 whichextends well into the pipe 3 connected to the suction side of the pump so that the chlorine will be drawn in with the solution and intimately mixed therewith while `passing through the pump and through the discharge' conduits 5, 6 and 7. The pipes 8, 5, 6, 8 and 10 have suitable valves therein for regulating the fiow of liquid therethrough.

ln the operation of theapparatusillu'sl trated, the alkaline solution, forA example,`

, milk-ot-lime is introduced into the mixing ulated amount through Y tank.

solution,

'tank'l Whichmay be, e. g.,

culated through the desired degree,

through the clean-off pipe 19.

about QO-ft. deep and which may Ahave a capacity ot say 12,000 gallons. rl`he liquid chlorine fro-m the 1 ton container 21 is introducedl in regthe expansion valve- 24 to the coil 25 which' may vhave a length-` for example of about --ft. 'such that the' liquid chlorine will be vaporized therein. The valves in the pipes 8 and 10 will be closed and those in the pipes 3 and 6 open, and the pump 4 Will be set in operation. The alkaline solution Will be drawn from the mixing tank through the suction pipe 3 and the chlorine gas will similarly be draWninto the pump from the nozzle 26 and the chlorine and alkaline solution Will be intimately mixed in the pump'and in the pipes 5, -6 and 7, and the mixture Will then be discharged through the pipe 7 intov the mixing This circulation will be continued until the alkaline solution has been chlorinated to the desired degree. AT he heat of reaction will be counteracted by the heat of vaporization of the chlorine, thus maintaining the temperature-of the solution below that which will cause objectionable decomposition.

When using milk-of-lime as the alkaline the solution Will be drawn off near the bottom where the undissolved lime will tend to accumulate so thatthe solution cirthe pump, and with which the chlorine is brought into intimate 4contact, Will tend to contain, an excess of the lime with which the chlorine can react, thus facilitating the operation.

When the solution has been chlorinated to the circulation" of the pump is stopped and the chlorine supply isv also cut 0H and the solution is permitted to settle to free it from undissolved lime or other impurities Which can be drawn off p rl`he clear settled chlorinated liquor can be drawn off through the pipe 9, the upperfend of which can be lowered for this purpose. In this case, the valves in the pipes 3 and 6 will be closed and those in the pipes 8 and 10 open, and the clear solution will then be pumped into the stock tank-or storage tank 14 fromv which it can be withdrawn as desired through the pipes 15v and 172 When one chlorine container has been eX- hausted it can be disconnected and another container supplied to take its place..

lit will thus be seen that the present invention makes use in a particularly advantageous way of the latent heat of evaporization of liquid chlorine to counteract the heat4 of solution of the chlorine and the heat 'of reaction between the chlorine andthe alkali of the solution, while the heat of the origildent. that solutions scribed. y

. poriziiig the chlorine,

nalsolution togethervvith the heaty of reaction are necessary to vaporlze thev liquid chlorine.

rlhe counteracting or neutralizing of the vheat'effects in this lWay is suchthat, lfor example,-a hypochlorite solution can be made vup With milk-of-lime and chlorineso as to made use of to supply the heat contain as much -as 100' grams or more of available chlorine per liter, and starting with the milk-of-lime at an initial temperature of about 20 C., the finall temperature Will not exceed about 30o content can similarly lution being reacted upon. The present inf vention greatly simplifies the utilization of liquid chlorine, as compared with the methods heretofore commonly employed, in that the heating of the liquid chlorine container itself (Where a relatively small container is employed is made unnecessary,

and in that a special evaporator, in conjunction With large chlorine containers, with special heating means for heating andvanecessary. This heating of a considerable quantity" of liquid chlorine- (which the present invention obviates) is attended with some danger, for example, incase the chlorine gas outlet becomes `accidently closed, or .incase the temperature rises tool high with the resulting production of excessive pressures :-e. g., 'at 100 C., the temperature of ordinary exhaust .or Wet steam, which is sometimes employed for heating liquidi chlorine to evaporate it, the pressure o liquid chlorine is vapproximately 613 lbs.'

persquare inch. The heating of such large bodies of chlorine, With attendant danger,

is avoided-by the present invention which introduces the liquid chlorine directly into, or ,intoheat interchanging relation with, the alkaline solution. The cooling of the alkaline solution which is thus brought about, involves a further simplification of the operation, in that other cooling means, such' as have heretofore been employed, are disensed with.

It will thus be seen vention presents advantages both in the -handling of liquid chlorine and in the utili- C. lt Will be evidecreased chlorine be produced, either di-V rectly'by chlorination of the alkaline soluis similarly made un- I that th'e present in- :iroV

iis

izo

zation'of the chlorine for chlorinating' the alkaline solution. The cooling of the solution, which is not only desirable but necessary for preparing strong bleach solutions,

is combined in a particularly advantageous. Way With the heating of the liquid chlorine to bring about its Vaporization, While the diiculties heretofore met with in handling liquid chlorine, and the expedients hereto'- fore resorted to, are avoided. A

Il claim: 1. The method of preparing bleach solutions by subjecting alkaline solutions to the action of chlorine, which comprises sup lying the chlorine in the `form of liquid c lorine, and utilizing the heat of Vaporization ofthe chlorine to cool thealkaline solution.

2. The method of preparing bleach solutions by subjecting alkaline solutions to the action of chlorine, which comprises supplying the chlorine in the form of liquid chlorine, and utilizing the heat of vaporization of the chlorine to cool the alkaline solution, the liquid chlorine being vaporized by indirect contact with the solution and being then introduced in gaseous form into the solution.

3. The method of preparing bleachsolutions by subjecting alkallne solutions to the action of chlorine, which comprises supplying the chlorine in the form of liquid chlorine to cool the alkaline solution, the liquid chlorine being vaporized by indirect contact With the alkaline solution.

4. The method of preparing bleach solu: tions by subjecting alkalineI solutions to the action of chlorine, which comprises cooling the alkaline solution undergoing chlorination by indirect contact with liquid chlorine undergoing vaporization.

5. The method of preparing bleach solu,

tions by sub-jecting alkaline solutions to the action of chlorine, which comprises circulating the alkaline solution from and to a miX ing tank by means ofa pump, supplying the chlorine in the form of liquid chlorine and circulating. it into indirect contact with the solution .anda thereby Vaporizing the chlorine and cooling the solution, and discharging the vaporized chlorine into the circulating liquorwhereby the chlorine is in-`4 timately admixed with the solution by means of the pump. v

v6. The method of prepanng bleach solutions by subjecting milk-of-lime to the action of chlorine, which comp-rises supplying the chlorine in the form of liquid chlorine and utilizing the heat of vapoirization ofthe chlorine to cool theQmilk-of-lime solution undergoing chlorination.

7. The method of preparing bleach solutions by subjecting milk-of-lime to the action of chlorine, which comprises circulating the liquid chlorine in indirect contact with the milk-of-lime solution and' thereby cooling the solution and vaporizing the liquid chlorine, and then lintroducing'the vaporized Achlorine into the milk-of-lime vthe action of chlorine comprising a mixing tank, circulating means for circulating liquor from said tank through a. pump and back to the tank, and means for circulating liquid chlorine in indirect contact with the solution in said tank and then discharging the chlorine into said circulating means.

In testimony whereof I aiiix my signature.

JAMES H. MACMAnoN. 

